About CD4
This gene encodes the CD4 membrane glycoprotein of T lymphocytes. The CD4 antigen acts as a coreceptor with the T-cell receptor on the T lymphocyte to recognize antigens displayed by an antigen presenting cell in the context of class II MHC molecules. The CD4 antigen is also a primary receptor for entry of the human immunodeficiency virus through interactions with the HIV Env gp120 subunit. This gene is expressed not only in T lymphocytes, but also in B cells, macrophages, granulocytes, as well as in various regions of the brain. The protein functions to initiate or augment the early phase of T-cell activation, and may function as an important mediator of indirect neuronal damage in infectious and immune-mediated diseases of the central nervous system. Multiple alternatively spliced transcript variants encoding different isoforms have been identified in this gene. [provided by RefSeq, May 2020]

About Spark Red 718
Spark Red™ 718 is a brighter alternative to Alexa Fluor® 700, adding to the fluorophore options for the red laser that can detect antigens with lower expression levels. It can be used on a conventional cytometer with a 633 nm red laser and 720/45 filter set (or equivalent filter used to detect Alexa Fluor® 700) spectral cytometers with appropriate instrument settings. On conventional cytometers, Spark Red™ 718 can be utilized with both APC and APC/Cyanine7. On spectral cytometers, it can be unmixed from APC, Spark NIR™ 685, Alexa Fluor® 660, APC/Cyanine7, and APC/Fire™ 810. As spectral properties of Spark Red™ 718 and Alexa Fluor® 700 are nearly identical, using them together in a multicolor panel is not recommended. With a medium brightness, Spark Red™ 718 is best suited for detecting antigens with low to moderate expression levels.